With the 45-70, limitations are all on the part of the shooter. The 45-70 had killed buffalo well past 600 yards. However the buffalo hunters were skilled shooters who knew their guns and sight well. They were also shooting Black powder which brings out the best in this cartridge which was designed for Black Powder. However for uf modern hunters who do not shoot as much as they did and are used to flat shooting sighted guns, it a different story. 200 yards is doable with good loads but 150 yards is better and I would always try to get that close .OR Closer. I love the old 45-70 and have taken rattle snakes to big bears with several of them. For big critters I like the 350 grain Hornady RN at about 1800-2000 fps. Good cast bullets are even better. I like a 405 to 465 grain Hard cast Gas Checked bullets.